Expression of the sexual state in Sagittaria latifolia* 
Joun H. SCHAFFNER 
In 1921, the writert published a paper on the nature of sexual 
expression in those plants which have a definite reversal of sex 
in the inflorescence, one part of the axis bearing staminate and 
the other carpellate flowers. Sagittaria latifolia Willd. was 
mentioned as being a plant of this type with carpellate flowers 
below and staminate flowers above. 
During the past summer the opportunity was presented for 
an extensive study of this plant in the field, observations being 
made in Ohio, Missouri, Kansas, and Colorado. As will be seen 
from the facts presented below the development of flowers in 
Sagittaria agrees completely with the idea that sex is dependent 
on a functional state of the protoplasm and that when there is 
alternative sexual expression or sex reversal in the inflorescence 
axis there must be a neutral zone of tissue, of greater or less ex- 
tent, between the two parts. 
The inflorescence of Sagittaria is commonly a scapose, simple 
raceme with the flowers in whorls of threes. Quite frequently 
one or more members of the lowest whorl are developed as 
branches giving rise to a paniculate inflorescence, which probably 
represents a more primitive evolutionary stage. In the manuals, 
Sagittaria latifolia is described as normally monecious or occa- 
sionally diecious. Buchenau in “Das Pflanzenreich”’ also de- 
scribes it as ‘‘ Monoeca, rarius dioeca.”’ Probably this statement 
means only that entire inflorescences are known to be purely 
staminate or purely carpellate. Since the plant is perennial, 
stoloniferous and tuberiferous it would be difficult to determine 
whether entire individuals were staminate or carpellate unless 
the plants were subjected to experimental control. The stamen 
vestiges of the carpellate flowers are usually small and few in the 
lower flowers, while near the top of the carpellate inflorescence 
they are more numerous and more perfectly developed. Usually 
* Papers from the Department of Botany. The Ohio State University. 
oO. 145. 
+ ScHAFFNER, JoHNH. Reversal of the sexual state in certain types of 
monecious inflorescences. Ohio Jour. Sci. 21: 185-200. 1921. 
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